I believe many of the intellectuals behind the "pro-life" movement (and rest assured it is the intellectuals, not the masses, behind any political movement, whether it be pro-life or instigating a communist revolution) are not opposed to abortion per se.   Anti-abortion legislation is simply a tool by which they try to maintain a less sexually permissive society, believing that if women who fall pregnant outside of marriage are forced to endure pregnancy and likely child-raising alone, rather than being offered an easy way out, they will be less likely to have sex outside of marriage.   For this reason any method of contraception poses the same threat to them as abortion does, though some methods may be easier to rally support against than others.
Label: Sarcastic